Question

How does the electronic configuration of ions vary with the configuration of their isoelectronic atoms? Who can explain with two examples and indicate the electronic configuration of ions along the series?

Answer 1

the term "isoelectronic" means that the particles have an equal number of electrons. Thus, an ion and an isoelectronic atom must have the same number of electrons. Then, the electron configuration of ions varies depending on the isoelectronic atom by the addition or removal of sleep electrons by the last occupied energy level to the structure of the isoelectronic atom.
Let's give the first example on lithium. The lithium atom has the following configuration:
+3Li 1s2 2s1. It is more energetically more advantageous to take one electron out of lithium, turning it into an ion Li+ with configuration: +3Li+ 1s2. Then the isoelectronic atom for the single-charged lithium ion will be helium with the configuration: +2He 1s2.
The second example is based on chlorine. The chlorine atom has the configuration:
+17Cl 1s2 2s22p6 3s23p5. It can be seen that one electron is not enough for chlorine until the p-orbit is completely filled, so it is more energetically more advantageous to attach one electron to the chlorine atom to the configuration: +17Cl- 1s2 2s22p6 3s23p6. The isoelectronic atom is argon with the structure: +18Ar 1s2 2s22p6 3s23p6.